The present invention relates an electronic musical instrument casing structure suited for application to electronic pianos having an outer appearance like that of a grand piano.
Heretofore, there have been known electronic pianos (electronic musical instruments) having an outer appearance like that of a grand piano, one example of which is disclosed in Japanese Patent Application Laid-open Publication No. 2007-233190 (hereinafter referred to as “the patent literature”). The electronic piano disclosed in the patent literature includes a casing structure where an accommodating section is provided behind a keyboard and surrounded by side plates defining an outer shape of the electronic piano. Back lid is provided on an opening portion at the top of the accommodating section in such a manner that it can open or close the opening portion as necessary. Plate-shaped member, referred to as “sound board” in the patent literature, having a plurality of speakers arranged thereon is provided within the accommodating section.
In the acoustic piano, where strings are provided within the accommodating section, a sound board corresponding to the aforementioned plate-shaped member is provided in the accommodating section beneath the strings and a frame. In the electronic piano, on the other hand, the plate-shaped member is provided near the top opening portion of the accommodating section close to the back lid.
Thus, when the back lid is in the opened position, the plate-shaped member undesirably appears on the exterior of the electronic piano; namely, the plate-shaped member is undesirably visible from outside the electronic piano.
Further, in the electronic piano disclosed in the patent literature, a fixation structure comprising fastener members, such as bolts, is used for fixing the plate-shaped member to side plates etc. of the body section of the electronic piano. However, because the plate-shaped member is an externally exposed component part in the electronic piano, the bolts fixing the plate-shaped member may also be undesirably visible from outside the electronic piano, which would undesirably impair the outer appearance of the electronic piano. Further, the plate-shaped member provided in the accommodating section is relatively large in size, and thus, if the plate-shaped member is fastened with many bolts, it must be bolted at many portions one by one over a relatively wide range, so that the mounting operations of the plate-shaped member would require much time and labor.
If the plate-shaped member is fixed by adhesive, no fastener members, such as bolts, would not be exposed outside of the electronic piano. However, such fixation by adhesive can not achieve a high degree of freedom of mounting and connection between the component parts of the electronic piano. Further, the fixation by adhesive alone may not be able to fix the component parts with a sufficient strength.
Further, if the plate-shaped member is formed of a natural material, such as wood, there would occur a deviation, from a designed size, of an actual size of the plate-shaped member. Thus, it is desirable that the fixation structure for the plate-shaped member be one capable of absorbing (tolerating) as much as possible influences of a deviation in actual size of the plate-shaped member and deformation of the plate-shaped member. Further, if the plate-shaped member influences acoustic characteristics of electronic component parts, such as the sound board, it is desired that the fixation structure for the plate-shaped member be constructed so as to enhance an acoustic effect of the casing including the plate-shaped member.